1. Field of the Invention
The invention relates in general to lighting devices and in particular to lighting devices improving cooling efficiency.
2. Description of the Related Art
Referring to FIG. 1, U.S. Pat. No. 6,902,291 discloses a conventional lighting device 10 primarily including a light source 12, a light transformer 14, a circuit board 16, a holder 18, a cooling device 20, and a heat sink 26. The light source 12 is connected to the circuit board 16 at the bottom of the holder 18. The light transformer 14 is mounted on the holder 18 for guiding light from the light source 12. The cooling device 20 is connected to the holder 18 and the heat sink 26 via substrates 22 and 24, respectively, such that heat can be transferred from the light source 12 to the heat sink 26, preventing overheat of the light source 12.
Generally, the substrates 22 and 24 are attached to the holder 18 and the heat sink 26 by adhesive or soldering. As conventional adhesive and soldering materials may increase production cost, assembly complexity, and thermal resistance, they are not suitable for compact lighting devices.